THESE TERMS GOVERN YOUR USE OF THIS DOCUMENT
Your use of this Ontario Geological Survey document (the “Content”) is governed by the terms set out on this page (“Terms of Use”). By downloading this Content, you (the “User”) have accepted, and have agreed to be bound by, the Terms of Use.
Content: This Content is offered by the Province of Ontario’s Ministry of Energy, Northern Development and Mines (ENDM) as a public service, on an “as-is” basis. Recommendations and statements of opinion expressed in the Content are those of the author or authors and are not to be construed as statement of government policy. You are solely responsible for your use of the Content. You should not rely on the Content for legal advice nor as authoritative in your particular circumstances. Users should verify the accuracy and applicability of any Content before acting on it. ENDM does not guarantee, or make any warranty express or implied, that the Content is current, accurate, complete or reliable. ENDM is not responsible for any damage however caused, which results, directly or indirectly, from your use of the Content. ENDM assumes no legal liability or responsibility for the Content whatsoever.
Links to Other Web Sites: This Content may contain links, to Web sites that are not operated by ENDM. Linked Web sites may not be available in French. ENDM neither endorses nor assumes any responsibility for the safety, accuracy or availability of linked Web sites or the information contained on them. The linked Web sites, their operation and content are the responsibility of the person or entity for which they were created or maintained (the “Owner”). Both your use of a linked Web site, and your right to use or reproduce information or materials from a linked Web site, are subject to the terms of use governing that particular Web site. Any comments or inquiries regarding a linked Web site must be directed to its Owner.
Copyright: Canadian and international intellectual property laws protect the Content. Unless otherwise indicated, copyright is held by the Queen’s Printer for Ontario.
It is recommended that reference to the Content be made in the following form: Freeman, E.B., ed. 1978. Geological Highway Map, Southern Ontario; Ontario Geological Survey, Map 2418, scale 1:800 000.
Use and Reproduction of Content: The Content may be used and reproduced only in accordance with applicable intellectual property laws. Non-commercial use of unsubstantial excerpts of the Content is permitted provided that appropriate credit is given and Crown copyright is acknowledged. Any substantial reproduction of the Content or any commercial use of all or part of the Content is prohibited without the prior written permission of ENDM. Substantial reproduction includes the reproduction of any illustration or figure, such as, but not limited to graphs, charts and maps. Commercial use includes commercial distribution of the Content, the reproduction of multiple copies of the Content for any purpose whether or not commercial, use of the Content in commercial publications, and the creation of value-added products using the Content.
Contact:
FOR FURTHER PLEASE CONTACT: BY TELEPHONE: BY E-MAIL: INFORMATION ON The Reproduction of ENDM Publication Local: (705) 670-5691 the EIP or Content Services Toll-Free: 1-888-415-9845, ext. 5691 [email protected] (inside Canada, United States) The Purchase of ENDM Publication Local: (705) 670-5691 ENDM Publications Sales Toll-Free: 1-888-415-9845, ext. 5691 [email protected] (inside Canada, United States) Crown Copyright Queen’s Printer Local: (416) 326-2678 Toll-Free: 1-800-668-9938 [email protected] (inside Canada, United States)
THE GEOLOGIC SETTING OF ONTARIO The Precambrian Canadian Shield arches across Ontario separating Phanerozoic basinal accumulations of sedimentary rocks. Based on age, degree of metamorphism, and structural differences the Canadian Shield has been subdivided into geological provinces. Three of these geological provinces exist within Ontario. The oldest, largest, and most northerly is the Superior Province. South of the Superior Province exist the relatively unmetamorphosed rocks of the Southern Province and the generally highly metamorphosed rocks of the Grenville Province. Within the northern portion of the Canadian Shield lie the Hudson Bay and Moose River Basins. On the western, southern, and southeastern margins lie, respectively, the Williston, Michigan, and Appalachian Basins. Within the area of the Geological Highway Map Southern Ontario are the Precambrian rocks of the Southern Province and Grenville Province of the Canadian Shield. Overlapping onto these rocks, are the almost exclusively sedimentary Paleozoic rocks deposited within the Michigan and Appalachian Basins.
Map 2418 ______SOURCES OF INFORMATION______Ontario Geological Survey Geology compiled from published and unpublished maps of the Ontario Geological Survey and the Geological Survey of Canada. The following general references contain additional information about the geology and landforms of southern Ontario. Chapman, L. J. & Putnam, D. F. (1966) The Physiography of Southern Ontario; Univ. Toronto Press. A 4 map set (scale 1" to 4 mi.) accompanies this text and is available from the Ontario Ministry of Natural Resources. Chapman, L. J. (1975) The Physiography of the Georgian Bay-Ottawa Valley Area; Ontario Ministry of Natural Resources, GR 128. Hewitt, D. F. & Freeman, E. B. (1972) Rocks and Minerals of Ontario; Ontario Ministry of Natural Resources, GC 13. Douglas, R. J. W., ed. (1970) Geology and Economic Minerals of Canada; Geological Survey of Canada, Econ. Geol. Rept. 1. Cartography and design by M. J. Colman, Surveys and Mapping Branch, Ministry of Natural Resources, 1978. Highway basemap supplied by Surveys and Plans Office, Ministry of Transportation and Communications, 1977.
Parts of this publication may be quoted if credit is given to the Ontario Geological Survey. It is recommended that reference to this map be made in the following form: Freeman, E. B., ed. 1978: Geological Highway Map, Southern Ontario; Ontario Geological Survey, Map 2418. PURPOSE OF MAP ' The most travelled and populated portion of Ontario lies south of highway 17 and east of Sault Ste. Marie. The purpose of the Geological Highway Map Southern Ontario is to present the general geology of this part of Ontario in relation to the familiar reference points of our highways, lakes, rivers, and communities. It is hoped that the information shown here will be of interest to the general travelling public, to students of the earth sciences, and to professional geologists. The Geological Highway Map shows by the use of colour the succession and distribution of rock units exposed at the surface. The oldest are metamor phosed volcanic rocks (unit 1) northeast of Blind River, and the youngest are the marine shales and sandstones of the Port Lambton Group (unit 38) south of Sarnia. The rock unit boundaries shown on the map have been determined or interpreted from mapping these rocks where they occur exposed in excavations or where they outcrop naturally at the surface. All of the rock units are partly covered by deposits laid down during the Quaternary glaciations, these surficial deposits consist of glacial tills and associated lake and stream deposits. They are not shown on the main map, although some are indicated on the physiographic map. All landform features, such as escarpments, canyons, hills, and valleys reflect variations in the underlying rock units and the geological processes including glaciations which have acted upon them. It is hoped that the landforms seen on your travels become more meaningful as their relationship to bedrock or geological processes is noted.
G eological
THE GEOLOGIC COLUMN OF TIME AND ROCK UNITS Colours and numbers are used here to represent rocks of a particular type or age. However, it should be noted that these colours usually bear no relation to the Highw ay M ap: actual colour of the rock in its outcrop. Each colour has been given a number. S o u t h e r n These numbers reflect the general sequence of rock formations with 1 being the oldest (first formed) and 38 being the youngest (last formed) rock unit shown on the map. Note that some of the rock units of the Precambrian Era may have formed simultaneously. O n t a r i o Where possible, ages in millions of years as determined by isotopic (radio metric) methods are listed in the column of time and rock units. The time relationships are best understood within the Phanerozic rock sequence and a special time column appears for these rocks. The Phanerozoic rocks are not only more recent, but contain abundant fossil life forms. From analysis of fossils and other data these rock layers have been separated into units (normally called Formations) that can be identified within widely separated outcrops. The colours on the map do not represent uniform rock compositions. Changes occur related to the rate of cooling (in igneous rocks) and to the distance from the source area (in sedimentary rocks). For example, the Lower Silurian Clinton and Cataract Groups change from dominantly sandstone-shale units in the Niagara Peninsula area to dominantly dolostone units in the Bruce Peninsula area. The distribution pattern of the coloured units (= rock units) shown on the map have been influenced by several factors: 1) the dip (tilt) of the rock layers and their thickness 2) the hardness of the rock units and their resistance to erosion 3) the topography of the land surface. Faulting (the cracking and movement of the Earth’s crust that often produces earthquakes) has affected Ontario throughout its history. Locations of the major faults within southern Ontario are shown by blue dashed lines. Faulting in Ontario has affected human history as well as geological history. For example, subsidence of the land associated with faulting created the valley lowlands of the Ottawa, Mattawa, and French Rivers. It was this fault induced river and lake lowland system that provided the access, settlement, and historical development of North America’s interior. Fortunately faulting is presently infrequent and of small scale within Ontario. Thus, property damage from faulting has been slight in comparison with other areas of the Earth.
PHYSIOGRAPHIC MAP Physiographic maps subdivide the landscape on the basis of geology and landforms. Two major physiographic regions exist in southern Ontario: the Canadian Shield Region composed of Precambrian-age rock units, and the St. Lawrence Lowlands underlain by rock units younger than 570 million years (Phanerozoic age). The Shield Region is subdivided into Provinces based upon age, degree of metamorphism, and structural variation. In turn, these provinces are subdivided on the basis of landform characteristics. The following subdivisions occur within southern Ontario: CANADIAN SHIELD ST. LAWRENCE LOWLANDS Southern Province Central St. Lawrence Lowland Penokean Hills West St. Lawrence Lowland Grenville Province Laurentian Highlands Southern Ontario’s major landforms are due to either erosion (lakeshores, escarpments) or glacial deposition (moraines, drumlins, eskers).